Another P0171 code...

Originally Posted by jfoj

Do you have just a broken flapper or do you also have a blown vacuum diaphragm as well?

The DISA can play some crazy games with the intake performance, cannot say for absolute certainty that the broken DISA flap can and will cause a lean code on only one bank, but you need to get everything sorted out to continue to rule out specific issues.

Depending on mileage, not a bad idea to replace O2 sensors, recommended at 100k miles anyway, fresh O2 sensors usually do not resolve lean codes, they usually help you see how bad things really are regarding fuel mixture issues.

Well, after I reset the lights, I actually am now getting lean codes on both banks, and other numbers consistent with a vacuum leak (see my above post). I don't think the O2 sensors are the problem. They're both behaving the same, and as you'd expect for a lean condition. Also, my code scanner has a specific O2 sensor test that includes the response time. Cool. Also, DISA diaphragm appears to be working well. And the pivot arm was completely circular--I doubt it's been working for quite some time.

Anyway, as I dug deeper I realized a couple of things:
1) I didn't actually remove the CCV lower hose
2) My dipstick O-ring is shot
3) Found an obvious broken hose at the SAP--from what I've read though, this shouldn't cause a code?
4) While trying to inspect another hose (looks like it comes from the CCV?), I broke it taking it off. Don't know if it was already cracked.

I had to put everything back together, as I ran out of time to work on it. So I'll be ordering both CCV hoses, the DISA repair kit, dipstick o-ring, and I may just get some stock hose for the SAP hose. Still not sure that I found my problem, even though I'm finding problems

CCV lower oil return line is one hose that often gets overlooked.

Originally Posted by jfoj

CCV lower oil return line is one hose that often gets overlooked.

I'm going to order it and replace when I go back in there. I couldn't figure out where exactly the CCV was. Looked like the lower return hose disappeared under the intake. Gonna have to get at it anyway to replace the upper hose.

Lower CCV hose is easy to find, it is the hose that connects to the dipstick at the base just before it drops into the crankcase. Follow the hose back toward the front of the car, you will then find the bottom of the CCV. Feel with your hands, if there is oil all over the hose, likely it is torn/collapsed at the base of the CCV.

Replacement hose is about $15 as I recall? I think you can also use 3/8" fuel line as well if you are in a bind.

Originally Posted by nola mike

1) I didn't actually remove the CCV lower hose
2) My dipstick O-ring is shot
3) Found an obvious broken hose at the SAP--from what I've read though, this shouldn't cause a code?
4) While trying to inspect another hose (looks like it comes from the CCV?), I broke it taking it off. Don't know if it was already cracked.

Well, there is your problem(s). Good luck putting back that CCV to Vanos hose back (number 4). It'll be a PITA. There should be a number on that hose indicating the manufacturing date. If there isn't one, you have a stock hose, which means that the hose and the rest of the CCV system is as old as the car. Might as well bite the bullet and replace the entire CCV system along with hoses.

Broken SAP hose will cause a lean condition.

Originally Posted by SeanC

Well, there is your problem(s). Good luck putting back that CCV to Vanos hose back (number 4). It'll be a PITA. There should be a number on that hose indicating the manufacturing date. If there isn't one, you have a stock hose, which means that the hose and the rest of the CCV system is as old as the car. Might as well bite the bullet and replace the entire CCV system along with hoses.

Broken SAP hose will cause a lean condition.

I thought the broken SAP hose would only lean out while the SAP was running at startup?

Anyway, replaced the above items, and all seems well. Yeah, that #4 item was a huge PITA to get to. The lower hose was soft, but didn't have any obvious holes. I'm now getting STFTs generally <3%. At idle it's -.8 to +.8 (in the high teens/low 20's prior). LTFTs are now around 5 (10 before). 600 miles with no codes now.

There is a "one-way" mechanical valve that connects the SAP hose to the intake manifold in the back of the engine. Since it is a mechanical valve (opens when you blow air to it, etc.), It will momentarily open under driving conditions and cause a lean condition. Ideally it should only lean out when SAP is running (when the valve is open).

SAP vacuum hose should only cause lean problems on cold start for the first 90 seconds if it is broken. Also I think the later version 330 did not have vacuum controlled SAP, these actually have a MAF for to measure the SAP airflow, you can tell because the hose from the SAP pump to the check valve does not have standard hose clamps, it has plastic quick release type clamps.

You also need to to check the vacuum hose at the fuel filter for the fuel pressure regulator as this breaks quite often as well.

Do not get overly excited about your O2 sensors at this point, might be wise to replace them, but they will do nothing for your overall lean condition, they just may react faster and be more active.

Fuel trims are heading in the right direction. You still may have a few issues to sort out with crankcase air leaks, valve cover gasket, oil fill cap, dipstick O-ring at block DISA O-ring or others. I usually prefer to see my fuel trims in the +2% or lower range, even long term.

You may also want to replace your fuel filter and check the 2nd link below in my signature for fuel pump issues.

Well, we're certainly good enough for now. Everything I've read says that LTFTs less than 8 or even 10 are OK. The fact that the STFTs are just about 0 at idle tells me that I don't have much if any remaining vacuum leak. Though I always thought that the LTFTs were just averaging the STFTs over time. Doesn't look like this is the case necessarily. Also, my LTFTs go down when I'm cruising 80+ on the highway, and seem to increase at 50-60 mph back roads--but that may make sense, as I'm not steady-state on those roads. Lastly, I did replace the dipstick o-rink and DISA o-ring. Oh, and I'm not at all concerned with O2 sensors--that was covered earlier in the thread. My scanner has an O2 sensor test mode that checks the reaction speed, and they check out. Although a code should be thrown anyway for a lazy sensor.

Not sure where your fuel trims really are, however, suggest you read my comments in this thread - http://forum.e46fanatics.com/showthr...034&highlight=

Originally Posted by nola mike

Well, reset the light. No recurrence after about 50 miles mixed driving.
@jfoj: Yeah, everything will eventually need replaced, but I'd rather not mess with it if a) there isn't anything wrong (yet), b) it's something that gives warning before it breaks, and c) it won't leave me stranded. Out of all the possibilities, only fuel pump meets c). Interesting link on the FP--my tank had a bit over 1/4 when the SES came on. I'll check the hidden data.
Since my experience with this car (and BMW's) is somewhat limited, I'm basing this off of prior cars--a vacuum leak should trip a lean code at idle. If it's huge, it will have driveability issues. At speed the effect of a vacuum leak is much less pronounced. If it happens again, esp at speed, I'll replace the FP.
.

Well, the car had been running fine. Ironically enough, it took less than 3 months after this reply of mine for the fuel pump to die unexpectantly and leave me stranded

So you were right about the FP. I was surprised that I got NO warning about this. Car running fine, started it up, had low power for a few hundred feet. I turned it off and it wouldn't restart. So maybe this is something to replace as preventative maintenance...
Many miles and no more codes though!